package org.shop.controller.user;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 产生随机验证码
 * 
 * @author Administrator
 * 
 */
@WebServlet("/code.png")
public class CheckCodeServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;

	// 设置字母的大小,大小
	private Font mFont = new Font("Times New Roman", Font.PLAIN, 17);

	// 随机产生颜色
	Color getRandColor(int fc, int bc) {
		Random random = new Random();
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}

	@Override
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		// 设置头信息:设置页面不缓存
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);

		// 表明生成的响应是图片
		response.setContentType("image/jpeg");

		// 在内存中创建图象
		int width = 100, height = 18;
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

		// 获取图形上下文
		Graphics g = image.getGraphics();
		// 实例化随机类对象
		Random random = new Random();

		// 设定背景色
		g.setColor(getRandColor(200, 250));
		g.fillRect(1, 1, width - 1, height - 1);

		// 画边框
		g.setColor(new Color(102, 102, 102));
		g.drawRect(0, 0, width - 1, height - 1);

		// 设置字体、颜色
		g.setFont(mFont);
		g.setColor(getRandColor(160, 200));

		// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
		for (int i = 0; i < 155; i++) {
			int x = random.nextInt(width - 1);
			int y = random.nextInt(height - 1);
			int xl = random.nextInt(6) + 1;
			int yl = random.nextInt(12) + 1;
			g.drawLine(x, y, x + xl, y + yl);
		}

		// 从另一方向画随机线
		for (int i = 0; i < 70; i++) {
			int x = random.nextInt(width - 1);
			int y = random.nextInt(height - 1);
			int xl = random.nextInt(12) + 1;
			int yl = random.nextInt(6) + 1;
			g.drawLine(x, y, x - xl, y - yl);
		}

		// 生成随机数,并将随机数字转换为字母
		String sRand = "";
		for (int i = 0; i < 6; i++) {
			int itmp = random.nextInt(26) + 65;
			char ctmp = (char) itmp;
			sRand += String.valueOf(ctmp);
			g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
			g.drawString(String.valueOf(ctmp), 15 * i + 10, 16);
		}

		// 把随机产生的六位字符设置在会话中
		HttpSession session = request.getSession(true);
		session.setAttribute("rand", sRand);

		// 图象生效
		g.dispose();
		// 输出图象到页面
		ImageIO.write(image, "JPEG", response.getOutputStream());
	}

}
